Focus on low pulse. A normal angiogram does not mean that you could not have problems from low heart rate. You should focus on the heart rate of 28 bpm. How long did you have this low heart rate (seconds, minutes or longer) and did you feel weak and dizzy during the low heart rate. If this cannot be answered you may need a ambulatory telemetry monitor for a couple of weeks or longer.

Was it really 28? If so, your markedly slow heartrate, is likely to be the cause of your symptoms, which are potentially dangerous. If your heart rhythm hasn't been studied with telemetry or holter monitoring, it should be. It is possible to correct slow rates using certain medications or a pacemaker.